1. Field of the Invention
The present invention relates to a process for the synthesis of aromatic aldehydes from highly reactive aromatic starting compounds by treating the aromatic starting compound with formamidine acetate and an acid anhydride to produce an aromatic aldehyde bisacylaminal which yields the aldehyde on hydrolysis in aqueous acid.
At present the Vilsmeier-Hack reaction is generally used to produce such aldehydes. The Valsmeier-Hack reaction uses POCl.sub.3 and dimethyl formamide as the active reagents and the reaction is sensitive to temperature control. If the reaction has an uncontrolled exotherm, dimethylcarbamoyl chloride, which is carcinogenic, may be generated. Further, the products often require purification before use in dye manufacture. Also, large amounts of H.sub.3 PO.sub.4 are formed which must be disposed of.
2. Description of the Prior Art
The reaction of diphenylformamidine with aromatic phenols in aqueous acid solution to produce aldehydes is known. R. Kahn and H. A. Staab, Ber. 87 272 (1954); F. B. Dains, Ber. 35 2504 (1902); J. B. Shoesmith and J. Haldane, J. Chem. Soc. 2704 (1923).